This invention relates to a high-temperature sliding alloy used in an oxidizing atmosphere under a high temperature condition ranging from a room temperature to a high temperature, and also relates to a sliding contact structure comprising a sliding member, made of this sliding alloy, and a mating member disposed in sliding contact with the sliding member.
Conventional high-temperature sliding alloys are disclosed, for example, JP-A-5-17839 and JP-A-7-292430 filed by the Applicant of the present application. These sliding alloys have a structure in which Co--Mo--Cr--Si base hard particles are dispersed in the matrix of Ni base alloy.
The sliding alloy, disclosed in JP-A-5-17839, consists of, by weight, 9 to 30% Cr, 5 to 19% Fe, 0.1 to 1.5% Si, 2 to 22% Co, 1.4 to 11% Mo, and the balance Ni and unavoidable impurities, and has the structure in which 5 to 35% by volume of Co--Mo--Cr--Si base hard particles are dispersed in the matrix. This sliding alloy is suitably used particularly when a mating member is made of a hard material, such as a precipitation hardening-type Ni base heat-resistant alloy, having a hardness of Hv300 to 500, and for example, this sliding alloy is suitably adapted to an exhaust gas control valve of a petrol (gasoline) or a diesel engine, and a variable valve in a gas turbine.
The sliding alloy, disclosed in JP-A-7-292430, consists of, by weight, 2 to 8% Cr, 2 to 10% Fe, 0.1 to 1.5% Si, 2 to 22% Co, 1.4 to 11% Mo, and the balance Ni and unavoidable impurities, and has the structure which comprises 5 to 35% by weight of Co--Mo--Cr--Si base hard particles dispersed in the matrix. Even when a mating member is made of a soft material such as austenitic stainless steel, this sliding alloy alleviates wear of the mating material, and therefore there can be achieved a sliding contact structure, comprising a sliding member (made of this sliding alloy) and the mating member disposed in sliding contact therewith, which sliding contact structure is excellent in durability.
A bearing for use in a carriage for charging a product to be heat treated into a heat treatment furnace, is required to possess excellent bearing properties (such as wear resistance) not only under a high temperature condition in the furnace but also under a room temperature condition.
However, the above conventional sliding members exhibit excellent sliding properties at a high temperature, but the sliding properties and particularly the friction coefficient have been found not entirely satisfactory at a room temperature.